The present invention relates to a method and system for operating a cooling fan within a computer system. More particularly, it relates to controlling cooling fan speed based upon power supply load and temperature for improved acoustic performance.
Computers or computer systems are extremely prevalent in today""s society, and are configured for a wide variety of applications. To this end, computer systems have traditionally been categorized as either low-end or high-end, based upon hardware capabilities and user application. For example, low-end computer systems typically refer to personal computers or desktop computers, utilized for relatively standard applications, such as word processing, spread sheet applications, internet navigation, etc. Low-end computers are commonly used in an office environment, in close proximity to one or more office occupants. Conversely, high-end computer system include network servers and advanced standalone computers having processor capabilities able to operate complex programs such as finite element analysis, CAD applications, etc. For most business applications, these high-end computer systems are typically located in a separate room (e.g., a server room) as a separate workstation area.
Regardless of the end application, the electronic hardware, including processor(s), power supply unit(s), etc., associated with a computer system generates heat. Heat is typically removed from the computer system by one or more cooling fans mounted in close proximity to the heat producing and/or heat sensitive components. Though performing a highly important function, the cooling fan(s) generates acoustic noise. For a computer system requiring a relatively large cooling fan, this noise can become quite loud.
The above-described fan-related acoustic noise problem has heretofore been relatively limited due to the work environments in which the particular computer system is placed. That is to say, low-end computer systems, although normally positioned in close proximity to one or more users, typically utilize a relatively small cooling fan due to the relatively small number and size of internal components. As a result, the acoustical noise generated by the low-end computer system cooling fan is virtually negligible. In contrast, while high-end computer systems entail large cooling fans, and thus elevated acoustical noise levels, these computer systems are normally positioned in remote computer rooms or areas that are separate from office occupants. As such, the acoustic noise associated with high-end computer systems did not cause user discomfort as the user(s) were not stationed in close proximity to the computer.
The continued advancement of the computer hardware technology has blurred the distinction between high-end and low-end computer systems. In particular, the hardware components associated with server-type computer systems has improved to the point that server technology can be implemented in less expensive and smaller platforms. As a result, the end-users are increasingly more inclined to use these high performance computers, otherwise adapted for network applications, as high-end personal computers in the ordinary work environment. In light of the above-described acoustic noise levels generated by these high performance, server-type computer systems, the opportunity for user discomfort increases dramatically as the user is now sitting in close proximity to the computer system. Further exacerbating this concern is the fact that processor advancements entail more closely packed conductors, necessitating use of even larger cooling fans and constricted, and thus even more acoustic noise.
Most conventional cooling fans associated with computer systems are run at a constant voltage. The fans and their operating voltages are selected so that adequate air flow/cooling is guaranteed for a computer system""s worst case cooling needs and ambient temperature conditions. The cooling fan automatically runs at a maximum speed, so that regardless of the actual heat generation, sufficient cooling is always provided. Often times, sufficient cooling can be achieved with much less air flow. Under these conditions, this means providing more air flow, and thus more acoustic noise, than is needed. Some cooling fans do provide a means of ramping up fan speed as a function of changes in ambient temperature conditions. However, the cooling fans are still configured so as to always assume a worst case of operating conditions (or maximum heat generation). Thus, even where the heat could adequately be removed at a lower speed, a cooling fan""s thermal ramp will begin at a relatively high speed, such that the airflow and acoustic noise produced by the fan are still significantly greater than otherwise required.
Pointedly, where a high-end computer system, otherwise designed for high performance activities such as network applications, is being used for low-end applications as described above, the cooling requirements are significantly lower than the worse case scenario. In general terms, the various internal components (e.g., processor) are operating/processing at lower than maximum speeds, drawing less power, and thus generate lesser amounts of heat. Unfortunately, because current fan control methodologies rely solely on ambient temperature to determine an appropriate fan setting, the cooling fan speed, and thus the acoustic noise, will always be higher than is otherwise necessary. It may be possible to provide two separate cooling fan control systems within a single computer, one for each type of end application (i.e., high-end and low-end). From a cost standpoint, this solution is not practical. A related concern arises in the context of computer manufacturer""s practice of simultaneously designing and developing multiple computer platforms utilizing the same basic component/chassis layout (e.g., a high-end platform and a low-end platform). The chassis and majority of hardware components are virtually identical for each platform; however, other components, for example the motherboard, are different. In the past, it has been necessary to design and provide a different cooling scheme for each platform, due to the vast difference in generated heat during use (e.g., the high-end platform motherboard can generate more heat than the low-end platform motherboard). Obviously, this entails additional costs and design time.
Computer system technology continues to evolve. The resulting increase in processing capabilities with a related decrease in size and cost has resulted in utilization of high-end computer systems in standard workplace environments, and thus in close proximity to users. Oftentimes, the computer system is being operated at less than full capacity, such that the fan speed and resultant acoustic noise is unnecessarily high. Therefore, a need exists for method and system of controlling a computer cooling fan relative to power supply load.
One aspect of the present invention relates to a method of controlling a cooling fan of electronic equipment including a power supply unit. The method includes sensing a power load of the power supply unit. A reference temperature of the electronic equipment is also sensed. Finally, a fan setting is determined based upon the sensed power load and the sensed reference temperature. By basing the fan setting on both reference air temperature and actual power supply lead, the method effectively minimizes cooling fan operation, and thus resulting acoustic noise, when the electronic equipment is operating at less than full capacity. In one preferred embodiment, a look-up table is provided in which a plurality of fan settings are included, each fan setting being based upon a correlation of power supply load and reference temperature. In another preferred embodiment, the electronic equipment is a computer system.
Another aspect of the invention relates to a method of controlling a computer system operating under normal conditions. The computer system includes a chassis maintaining a power supply unit, a temperature sensor, a central processing unit, and a cooling fan. In this regard, the cooling fan is rated to have a maximum operational speed that provides sufficient air flow/cooling when the power supply unit is operating at a maximum available power load. With this in mind, the method includes sensing a power load of the power supply unit. A reference air temperature of the computer system is sensed via the temperature sensor. Finally, the cooling fan is operated at less than the maximum operational speed when the sensed power load is less than a predetermined value and the sensed reference air temperature is less than a predetermined value. With this methodology, a high-end computer can readily be used in an office environment with minimal acoustic noise-related user aggravation, as the cooling fan is effectively prevented from running at a higher than necessary speed. In one preferred embodiment, the sensed power load is categorized relative the maximum available power load as either a high load or a low load. With this one preferred embodiment, where the sensed power load is designated as a low load, the cooling fan is operated at a lesser speed as compared to a speed at the same ambient temperature but high load.
Yet another aspect of the present invention relates to a computer system including a chassis, a central processing unit, a cooling fan, a temperature sensor, a power supply unit, a power load sensor, and a control device. The central processing unit is disposed within the chassis. The cooling fan is associated with the chassis. The temperature sensor is provided to sense a temperature of ambient air at the chassis. The power supply unit is coupled to the chassis for powering the central processing unit. The power load sensor is provided to sense a power load on the power supply unit. Finally, the control device is provided to control a speed of the fan. In this regard, the control device operates the cooling fan as a function of the sensed ambient air temperature and the sensed power load. With this construction, the control device effectively limits audible fan noise to a minimum.